Continuous process for making solid polymer



Oct. 5, 1948. P. J. GAYLOR 2,450,547

CONTINUOUS PROCESS FOR MAKING SOLID POLYMER Original Filed Dec. 8, 1941/NVE'NTOR Patented Oct. 5, 1948 CONTINUOUS PROCESS FOR MAKING SOLIDPOLYMER Peter J. Gaylor, Union County, N. J.

Original application December 8, 1941, Serial No. 422,137. Divided andthis application May 6, 1944, Serial No. 534,445

4 Claims.

This invention relates to chemical reactions in which liquid rawmaterials are converted to solids at the reaction conditions. It dealsespecially with a polymerization process for carrying out continuouslythe polymerization of unsaturated organic materials particularly at lowtemperatures.

At the present time there is no totally satisfactory method for thecontinuous polymerization of unsaturated materials to solid products.Various unsaturated mixtures have been polymer,- ized in the past bybatch methods into very high molecular weight substances in reactionvessels or containers of the batch type. In such batch type reactors,the polymerization of the various unsaturated compounds is carried out,for example, at low temperatures by the use of active halides orFriedel-Crafts type catalysts. This is particularly the case withisobutylene at temperatures ranging from C. to 100 C., under theinfluence of catalysts such as boron fluoride in the presence ofdiluent-refrigerants such as liquid propane, liquid ethane, liquidethylene and the like. They have also been applied to the polymerizationof olefinic mixtures such as isoolefins of the type of isobutylene inadmixture with diolefins such as butadiene, isoprene, pentadiene,dimethyl butadiene and the like, in the presence of similardiluent-refrigerants, employing a Friedel-Crafts type catalyst such asAlCla dissolved in a low freezing solvent such as ethyl chloride, methylchloride, carbon disulfide or the like.

In using the batch reactors of the prior art, considerable difiicultyhas been experienced in that the formed polymer particles or slurry hada tendency to coalesce and lump on the reactor walls into largeaggregates which necessitated the cleaning of the reaction vessel at theend of about every second batch in order to remove the clumped polymerparticles, particularly the lumped polymer particles on the side wallsof the reaction vessel, means in subsequent batch operations.Furthermore, in batch operations poisons tended to accumulate during thepolymerization resulting in the formation of soft lower molecular weightproducts which, due to their sticky nature, gave operating difficultiesof considerable magnitude. Moreover, the polymer formed tended to buildup on the well either below or above the liquid level of the reactionvessel or on the impeller arm above the liquid mixture level therebynecessitatin frequent'shutdowns in order to remove the adhering polymermasses and prepare the reaction so as not to impede the a tating vesselfor subsequent polymerization reactions.

An object of the present invention is to provide a continuouspolymerization apparatus for the rapid manufacture of polymers withminimum agglomeration in the reaction vessel, and minimum loss ofrefrigerant and solvent employed. Other objects will become apparent asthe description proceeds.

The objects of my invention are accomplished by passing the catalyst andsolvent together or separately, together with or separate from thereactant or reactants, into a reaction zone, the reaction ingredientscausing a swirling action so as to dispense with agitation, althoughagitation may be employed. The proper time of reaction is maintained byregulating the speed of the materials through the reaction zone.

I have found that by means of the device of the present invention,desirable high molecular weight polymers and interpolymers, particularlythose obtained at low temperatures, are formed in a fine slurry orpellet form distributed in the solvent and the unreacted liquid. Iseparate this solid from the liquids by passing the products immediatelyafter reaction over a foraminous member adjacent to the reactor. Otherobjects and details of the invention will be apparent from the followingdescription when read in connection with the accompanying drawingwherein is shown a semi-diagrammatic view in vertical cross-section of apolymerization reactor.

In the drawing is shown a desirable embodiment of the invention. Anouter casing 4, preferably of spheroidal shape, is mounted on supports2!. The lower portion of the outer casing is in the form of a foraminouswall .13, such as a screen, perforated plate, or the like, disposed andconstructed so that the reaction mixture passes over it without stoppageand the liquid and solid phases are substantially separated before thesolid phase reaches the bottom of the casing at discharge opening l1 anddrops into quench tank I6 which contains alcohol, water, or similardeactivating, neutralizing or hydrolyzing agent to remove or neutralizethe catalyst, acid, or other similar substance used in the reaction.Vent i8 is provided at the top of the quench tank to recover any vaporsgiven off.

Inside of the outer casing 4 and mounted therein by supports or brackets8, is reaction vessel l in which the reaction takes place. This vesselis preferably of metal such as iron, stainless steel, etc., but may beof any inert material capable of withstanding the reaction conditions.

It may be a shell, or it may be a hollow-walled invention, a suitablevessel, the hollow space 1 of which may be filled with insulation oremployed for introducing refrigerant or heating means, say in at pipe 9and out at pipe I to effect indirect heat exchange to the reactionmixture.

The reaction mixture, e. g. the reaction liquid or liquids, areintroduced through the top of outer casing 4 by means of pipe 3 intoreaction zone l8. Catalyst and solvent and/or refrigerant liquid may beintroduced through annular pipe 5 which terminates in the reaction zonewith an orifice 8 which imparts a swirling motion to the reactingliquids. The rate of introduction of the materials through pipes 3 and 5is controlled by the time of reaction required in reaction zone IS.

A sealed enclosure 22 is provided for collecting liquid dropping throughforaminous wall 43, and vent 24- allows gases and vapors to be drawn onthrough outlet ll together with those drawn oi! the top of the outercasing at II for recompression, after purification if necessary, andrecycling. Liquid may be recovered from outlet H and this may berecirculated to the reaction zone, preferably after removal of poisonswhich tend to accumulate, e. g. by filtration through active charcoal,distillation, or the like. Insulation I5 is provided for the outersurfaces in order to minimize heating or refrigeration losses. Solidproduct, and/or quenching liquid may be drawn of! recovery vessel It byopening 23.

In the operation of this embodiment of the quantity of the refrigerant,which may be liquid propane, liquid ethane or liquid ethylene, isdelivered .through the supply pipe 3 to the reaction vessel i. Thereaction ves- $81, which is preferably steel or other metal, is cooledrapidly by volatilization of the refrigerant (aided by the coolingeffect of liquid ethylene in the refrigerant jacket 1 through pipe 9)and the volatilized gas is discharged through an exit pipe in forcondensation and recycling or other use. When the reaction vessel andother members of the device are cooled to the desired low temperature,the desired quantity of unsaturate to be polymerized, e.- g. liquidisobutylene, is delivered through delivery pipe 3 to the reaction vesseland the catalyst is simultaneously delivered to the hollow shaft 5 theend of which in the reaction vessel is provided with anozzle, say with aA" hole through which the catalyst, either boron fluoride or a metalhalide (such as A1C13 dissolved in an alkyl halide), is forced underpressure through the hollow shaft at right angles to the swirlingreaction mixture. The swirling action created by the downward flow ofthe feed mixture and sudden impact with the bottom of the reactionvessel thereby results in simultaneous mixing of the catalyst with thereacting liquid, and the rapidly churning undercurrents of the reactionmixture produced in the reactor vmsel disperse the catalyst throughoutthe reaction mixture at an exceedingly rapid rate. The catalyst isdispersed in droplets so small or bubbles, if boron fluoride is used,that they are completely dissolved through the solution interface intothe reactant mixture before the polymerization has proceeded to such anextent as to make any substantial change in the concentration of thereactant adjacent to the interface of the bubble or droplet. Under theseconditions, complete polymerization generally takes placeinstantaneously.

The delivery of the catalyst through the hollow shaft is maintained at aproper concentration and continued until the desired polymerization ratehas been obtained, at which time the rate of feed and catalyst iscontinuously maintained. The polymer is formed in the reaction mixtureas a slurry or hard pellets and this mixture flows due to the force ofthe incoming reaction mixture over screen l3 which filters out theliquids, allowing the hard polymer pellets to discharge by'force ofgravity into a quench tank It containing an oxygenated organic liquidsuch as an alcohol, alkali or water or any other material for removingor hydrolyzing the catalyst.

By this procedure there is .thus readily obtained a continuousproduction of a finely divided, "cry high molecular weightpolyisobutylene. Since liquid ethylene is used as the refrigerant,giving temperatures of approximately 98 C. (ethylene alone boils atabout -103 C.) and high purity isobutylene is used with boron fluorideas the catalyst, the reactor, as shown in the drawing, is capable ofproducing polyisobutylene having molecular weights ranging from 100,000up to 300,000 or above, substantially free from undesirably lowmolecular weight sticky materials andwithout any tendency for polymeraccumulation in any part of the reaction vessel. The polymer as formedis in the form of fine discrete particles which lend themselves veryreadily to subsequent treatment.

This embodiment of the invention is also particularly advantageous forthe preparation of interpolymers of mixed olefins such as isobutylenewith a diolefin to give materials of high molecular weight, and lowunsaturation which can be cured with sulfur.

For this use, the reacting liquid feed entering through feed pipe 3 isfeed continuously to the reaction vessel. When internal refrigeration isused the refrigeration jacket 1 is insulated internally with a suitablematerial, although additional refrigeration may be provided in thisspace, and the feed which may be isobutylene and a diolefin such asbutadiene, isoprene, pentadiene or dimethyl butadiene in the proportionof from to 99 parts of the isobutylene with 20 to 1 part of the diolefinwith a sufiicient quantity of ethylene usually in the ratio of 2 partsethylene to 1 of reactants to serve as a diluent-refrigerant. To therection chamber I there is added a mixture of methyl chloride and theisoolefin-diolefin reactants in the proportion above mentioned, themethyl chloride in this case serving as a diluent, and the flow ofcatalyst consisting of aluminum chloride dissolved in methyl chloride toa concentration of 0.5 gram per 100 cc. is prepared and chilled to about-78 C. and discharged through feed pipe 5 at a rate of about 100 cc. perminute simultaneously with the feed-diluent mixture entering throughfeed line 3.

The interpolymer resulting from this polymerization, after beingquenched in tank I 6 to remove the catalyst and volatile unreactedmaterials has a relatively low iodine number and is reactive with sulfurand upon compounding and curing gives a vulcanizate which has an elasticlimit and a definite tensile strength.

Thus the invention provides a compact apparatus and process by whicholeflns or olefin-dlolefln mixtures are polymerized continuously to.nonsticky products at low temperatures with minimum losses of reactantsand refrigeration so that the unpolymerlzed liquid mixture and polymerformed will follow up the entire inner surface of the reactor wallgiving it a washing eifect and overflow to a reservoir without formingadhering clumps of polymer bodies on .the wall of the reactor vessel ordraw 01f discharge pipe.

' reaction,

The apparatus may be used for the polymerization of other unsaturatedcompounds which yield solid polymers or copolymers at reactiontemperature and which contain a liquid phase after e. g. styrene,acrylates and methacrylates, acrylonitrile, ethylene, vinylidinechlorides, olefin-diolefin resins, coumarone-indene resins, and the likeeither where the reaction is run in the cold or hot, although theapparatus is best employed for reactions run at low temperatures.

Other reactions which may be carried out in such an apparatus arecondensation reactions, dye reactions, etc.

One advantageous feature of the present invention is the fact that thewhole operation may be carried out under pressure without inconvenience.In other words, pressure may be applied to the outer casing 4, and thewhole reaction and separation system thus maintained under suchpressure, provision being made to shut off or bypass quench or productcollecting tank l6 intermittently to remove the product.

This is a division of my copending application Serial No. 422,137, filedDecember 8, 1941.

While there are disclosed but a limited number of embodiments of theinvention, it is possible to provide still other embodiments wihoutdeparting from the inventors concept herein disclosed. Other adaptationsare possible within the scope of the present invention.

I claim:

1. In the continuous process for producing a dispersed solid polymer,the particles of which tend to coalesce during removal from the reactor,said polymer being obtained by polymerizing a polymerizable raw materialin liquid phase at low temperature ranging from 0 C. to 100 C., with anactive halide catalyst of the Friedel Crafts type and forming a discretedispersion of solid polymer in liquid, the improvement comprisingcontinuously screening said polymer immediately after reaction while itis still at low temperature, to separate it from the liquid.

2. In the continuous process for producing a dispersed solid polymer,the particles of which tend to coalesce during removal from the reactor,said polymer being obtained by polymerizing a polymerizable raw materialin liquid phase at low temperature ranging from 0 C. to100 0., with anactive halide catalyst of the Friedel-Crafts type and forming a discretedispersion of a solid polymer in liquid, the improvement comprisingcontinuously screening said polymer immediately after reaction while itis still at low temperature, to separate it from the liquid, andrecycling at least a portion of the liquid to the polymerization zone.

3. Process accordin to claim 1 in which the polymerizable raw materialcomprises isobutene.

4. Process according to claim 1 in which the polymerizable raw materialcomprises a mixture of isobutene and a diolefin. 7

PETER J. GAYLOR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,041,502 Voss et al May 19, 19362,276,893 Thomas and Lightbow'n Mar; 1'7, 1942 2,317,878 Bannon Apr.27,1943 2,322,073 Thomas and Sparks June 15, 1943 2,334,195 Hopfi et a1.Nov. 16, 1943 FOREIGN PATENTS Number Country Date 483,453 Great BritainApr. 20, 1938 379,029 Italy Mar. 5, 1940 OTHER REFERENCES ChemicalEngineers Handbook by Perry, 2nd edition, Pp. 1658 and 1659, pub. 1941by McGraw- Hill, N. Y.

